Implementing the PSU on every kind of power amplifier is one of the most underestimated things with DIY audio and professional builders. The BMM electronics 2014 power supply is designed for use with the 4008 2 x 200W analogue power amplifier and is capable of delivering up to 14 Amp continuous current and 30 Amp peak current so this won’t be the problem. I think that the O88042 500VA 2 x 55V 4.55Amp transformer you use causes the problem in your application. In my opinion you should have used at least 800VA and best a 1000VA transformer.

Originally posted by ericpeters How is the temperature around the zappulse modules, I notice you don't use any specific cooling....just the bottom plate?

They get slightly warm but no more than that. From the ZAPPulse "cookbook" it says:

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Cooling requirements depends on the applied supply voltage, as most of the hear is generated in idle mode, with no load. If you want to be sure to have appropriate cooling, simply use a A5 size aluminium sheet per module, but less will do. A 200W stereo amplifier can be cooled just using the bottom of a thin steel sheet 19" rack enclosure. Even playing at full power for extended periods will not thermally overload the ZAPPulse amplifier. So the obvious cooling solution would be to place the modules on the enclosure floor or side walls. With smaller PSUs of +/- 35-40V which gives 50-80W into 8ohms no heat sinking is called for at all. Not all power is dissipated in the heat sink, some 3-5W are dissipated in the power resistors on the board and 1-2W in the filter choke all depending on signal load. A thermal protection circuit will shut the module down at around 100C.

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I also see you use both XLR and Cinch input parallel wired , do you hear any difference when you hook them both up at the same time?

I haven't tried that yet. I did it mainly for flexibility and also because I was thinking of using the RCA terminals for my AV setup (front channels) and XLR for stereo but I think I'll leave the AV going through the pre for better isolation (prevent ground loops caused by the AV gear being hooked up to CATV).

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are the speaker terminals WBT? I don't see them in your cost overview

Yes, they are WBT-0765 terminals and I forgot to include them because I got them through a friend. They cost me 71 Euros for the set of 4, including the small torx screws for securing the wires (I did this rather than soldering them).

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I've build an amp using the same modules but a higher voltage and lower spec'd power supply:

Probably because of the power supply specs the results are a bit dissapointing, I don't think the suplly has the current capacity as mentioned on this website.
I compared the amp with 2 rotel RB980BX and with one Krell KSA 80B and in both cases but of specifically in comparision with the krell the Zap had sharp treble and lacking bass pressure. Also at louder levels the zap started clipping sooner than the Rotel.

Hmm - 2*50VAC is right at the limit of what the ZAPPulse modules (even the "SE" version) can handle. 2*50VAC, rectified would give you +/-69VDC, giving 286Wpc into 8 ohms . The limit for the modules is +/-72VDC giving 290Wpc into 8ohms. It's possible that close to the limit they don't work so well.

well, a 230V AC PS is useless for me unless it runs on the plug I have my clothes dryer hooked up to Maybe for export they can leave that off. their reseller here in the US doesn't carry the crossover.

And just like you, I'd rather run it with a battery supply, just like my DAC. How do you get to the 15V? Are you using two 12V gel cells in series, regulated down to 15V? Probably needs quite the heat sink to do that.

well, a 230V AC PS is useless for me unless it runs on the plug I have my clothes dryer hooked up to Maybe for export they can leave that off. their reseller here in the US doesn't carry the crossover.

And just like you, I'd rather run it with a battery supply, just like my DAC. How do you get to the 15V? Are you using two 12V gel cells in series, regulated down to 15V? Probably needs quite the heat sink to do that.

Peter

If you could get the board you just need a trafo 115 V prim. and 15-0-15 V secondary

I use 4 x 12 V lead-acid batteries in series and regulates the 2x24 V down to 2x15V using lm317/lm337 and not really that much heat sink, but I will add more heat sink in the future - se the thread I started

Even though self-oscillating class-d amps have better PSSR than their carrier-based ones they still profit from a generously dimensioned PSU.
Keep in mind that the gain of the output stage is determined by the ratio of supply-voltage/carrier-signal (the latter measured at the input of the comparator).
With a more generously dimensioned PSU you have less "muddying-up" of the midrange by the LF signals.

A more generously built amp does generally play much more effortless than its weak counterpart.

The SE version uses Black Gate caps. According to LC Audio this makes it less susceptible to the PSU caps you use and alltogether improves the sound quality, particularly in the mid and high frequencies. The SE version can also handle a higher PSU voltage and therefore you can run it at a higher output power than the normal version.

LC Audio recommend using the normal version only for subwoofer applications and the SE for full range audiophile amplification.